In spite of an extensive literature and knowledge about the clinical manifestations, pathology, and seroepidemiology of CMV infections there is a great deal unknown about the transmission and epidemiology of this virus. This is in large part due to the ubiquitous nature of the virus, the high frequency of inapparent infections, the difficulty in rapidly identifying the virus in specimens, the prolonged periods of viral shedding by humans (months to years), and the lack of multiple serotypes for epidemiological studies. Because effective antiviral therapy is unavailable, control of CMV infection will require prevention of infection and studies of a CMV vaccine are in progress. The goals of our research are to utilize and develop the techniques of recombinant DNA technology for application in well defined and designed epidemiological studies on the transmission of human cytomegalovirus within the hospital. The specific objectives for this phase of our work are: 1) To confirm that we have accurately defined the major risk factors (low birth weight and absences of antibodies to CMV) for the morbidity and mortality caused by acquired CMV in premature infants by demonstrating that this infection can be prevented by supplying low birth weight infants born to seronegative mothers blood products from seronegative donors. 2) To precisely define the risk to hospital personnel of CMV acquisition by initiating a prospective study designed to document the rate of CMV infection per exposure. Analysis of the viral DNA genomes will be used to prove that hospital acquisition has occurred. 3) To investigate at least three different DNA hybridization techniques using cloned CMV DNA both as a means for possible rapid diagnosis and for strain differentiation, thus facilitating and improving the design and conclusions of our epidemiological studies. The results of these studies will define appropriate guidelines regarding CMV infections as well as help define rational guidelines regarding any potential use of a CMV vaccine.